1. Field of the Invention
The present invention relates to a toner.
2. Description of Related Art
Recently, for purposes of increasing a printing speed, increasing the number of usable types of paper, and reducing environmental load, there is a demand for reduction of thermal energy applied in fixing a toner image. In order to meet the demand, a technique to improve the low-temperature fixability of a toner is required, and as one of methods for achieving the technique, a crystalline resin having an excellent sharp melt property, such as crystalline polyester, is used as a binder resin.
For example, an electrostatic image developing toner using a binder resin containing a crystalline polyester resin and an amorphous resin is known. If a mixture of a crystalline polyester resin and an amorphous resin is used, a crystal portion of a toner particle is melted when the temperature of the toner particle exceeds the melting point of the crystalline polyester resin during heat fixing, and hence the crystalline polyester resin and the amorphous resin are compatibilized with each other. As a result, low-temperature fixability can be attained (see, for example, Japanese Patent Application Laid-Open No. 2006-251564).
On the other hand, there is also a demand for high image quality in recent years, and in order to meet with the demand for high image quality, examinations have been made on size reduction and spheroidization of a toner particle. The size reduction of a toner particle can improve the reproducibility of dots of a toner image formed on a surface of a photoconductor. Besides, the spheroidization of a toner particle can improve developability and transferability. As a result, fine-line reproducibility and printing performance can be improved.
Besides, there are known techniques to attain long-term stability in high image quality of a toner by focusing on an external additive adhering to a toner base particle. For example, a toner containing, as an external additive, deformed colloidal silica and a fatty acid metal salt particle is known. It is described that the toner can form high quality images for a long period of time and inhibit occurrence of cleaning failure (see, for example, Japanese Patent Application Laid-Open No. 2010-128216).
For supplying a toner to an image forming apparatus, a configuration in which a resin toner bottle containing a toner is loaded to replenish the toner is known. The toner reduced in size or spheroidized is, however, liable to be degraded in dischargeability from the toner bottle (hereinafter referred to as the bottle dischargeability). In particular, the toner using a polyester resin is liable to adsorb a water component, and hence the adhesion to the toner bottle is further enhanced, resulting in much more degrading the bottle dischargeability.